How To Persist Anonymous Types Instances Through NHibernate
Feb 12, 2010
Instinctively, I would say that this is impossible, as NHibernate needs to know some mapping information on how to persist a given type. Thus, I encountered some situations in which I could use such a feature. For instance, through a named query or something like so. On the other hand, using a named query would require me to make an addition to the configuration file.
Let's suppose we have an application interacting with some underlying datastore. This datastore is configured through the NHibernate configuration file. Then, I wish to have NHibernate load only a subset of an entity properties, from another subsystem to which my application shouldn't need to interact much, so it is not worthy to define classes for this system, as I only need a fraction of this alien system's information, let's say three out of thirty-two data columns. For that matter, if I chose to load only those three columns let's say for performance concerns, I would then use an anonymous type, perform the required action onto this information, then persist it back to the datastore. Now, it wouldn't be of much interest to do so if I only had one entity to get loaded from the datastore, so let's say I have about 75,000 rows to load into my process. I then shall consider this subset option very seriously!
What strategy should you choose in such situation, if you needed to persist these changes to a subset only of this entity's properties?FYI: I am asking because I must write specific rules of usage with NHibernate, such rules that even a beginner developer would even be able to use it without knowing too much about NHibernate, but only following the rules and guidance of the technical documents I have to produce.
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Dec 30, 2010
Are anonymous types slower than declarative types?
For example, does
Dim score as Double = CalculateScore()
run slower than
Dim score = CalculateScore()
Why use explicit typing if it's no slower?
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Sep 5, 2009
Assuming Anonymous Types are tailored to be used with LINQ, I'd like to use them for simply and fast data aggregation without an explicit class definition, like in this snippet[code]....
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Jun 29, 2009
I have a problem using linq and anonymous types in an asp.net vb.net application.When I write the code above, I have 2 errors :
- "declarations of variable with Option Strinct On requires an As clause"
- "the name 'item' is not declared"
Public Sub MyFunc(ByVal xe As System.Xml.Linq.XElement)
Dim lstitems = From it In xe.Elements Select txt = it.@Text, value = it.@Value
For Each item In lstitems
Dim s As String = item.txt
Next
End Sub
Does it mean that is not possible to use Option Strict On and Option Explicit On ?Or I make a syntax error ?Or is it just a bad configuration of my application ?
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Mar 19, 2010
I would like to use reflection on an anonymous type resulting from a LINQ to SQL query. I know that reflection on anonymous types works in general. The following code successfully generates a propertyinfo array with two elements:
Dim MyObject = New With {.Col1 = 1, .Col2 = "Test"}
Dim t As Type = MyObject.GetType()
Dim pilist As PropertyInfo() = t.GetProperties
[Code].....
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Jul 2, 2011
Supposing the referenced List below contains 2 elements:
Dim Countries = From c In List _
Select New With { .Country = c.Country, .CountryID = c.CountryID }
The code above returns
.Country=Spain .CountryID = 1
.Country=Spain .CountryID = 1
How can I get the distinct values? The Countries query should contain only
.Country=Spain .CountryID = 1
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Mar 11, 2009
Any best approach to what I'm trying to achieve (linq to sql, returning list of data to show in a grid/list etc etc)... Its complaining about anonymous type conversion, and from what I'm reading, thats not elegant way of doing it.
Public Function GetHistory(ByVal historyId As Integer) As List(Of ?????????)
Using dc As New myDataContext(Application.GetConnection)
Return (From t In dc.ActionTypes, a In t.MyTable Where a.HistoryID = historyId Select a.ActionOn, a.ActionBy, t.Description, a.ImpactedItem, a.ActionDescription).ToList
End Using
End Function
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Oct 25, 2011
I am in the process of learning LINQ to Objects. I am querying an array of reference elements using LINQ. In the code below, which I have marked with asteriks and PROBLEM, I am having difficulty returning any values for and I suspect its because of the multiple Select arguments.
'Program name:Querying an Array of Invoice Objects
'Created/revised:
'Project description:To demonstrate the use of LINQ to query objects
[Code].....
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Jul 14, 2011
I was toying around with some of the linq samples that come with LINQPad. In the "C# 3.0 in a Nutshell" folder, under Chater 9 - Grouping, there is a sample query called "Grouping by Multiple Keys". It contains the following query:
from n in new[] { "Tom", "Dick", "Harry", "Mary", "Jay" }.AsQueryable()
group n by new
{
[Code].....
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Jun 29, 2009
How to declare Anonymous types. I want to do a different query based on a condition.
Something like this:
If true then
Dim Myquery = From data In MyXML.Root.<hist> _
Select New With { _
.SensorID = CType(data.<sensor>(0), Integer)}
else
[CODE]...
Then I want to reference MyQuery outside of the condition. But how do I declare MyQuery outside of the if statement?
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Apr 24, 2012
I've got the below, where I'm grouping a collection by a propery, then wanting to access the properties of my group. Problem I have is with the anonymous typing. Because of option strict I have to give an explicit type but I can't work out what the type should be. The below doesn't compile because t.HeadAccountKey isn't a value (as t has a type of object). So either I need do some casting or my linq selector is wrong,
[Code]....
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Apr 24, 2012
The documentation has an example about grouping on multiple properties[code]...
Is it possible to rewrite the original query to just return IEnumerable(Of CustomerRegionGroup), or do I have to use the anonymous type, and run a second query on the result of the first?
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Jul 26, 2010
I'm trying to create a web site that users can log into and self serve their user information ie name, address etc. I've set up a SQL server DB with a couple of table holding the data and accessing those using Linq. I'm selecting specific data from my datacontext then trying to assign it to a label, ideally I want to assign the value to a class attribute so I can use the users details on multiple pages.
I've simplified the code (removing WHERE statement etc for the purposes of this question):
Using CurrentUserDataContext
As
New UserDataDataContext()
[Code].....
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Jun 29, 2010
I'm trying to translate some C# LINQ code into VB.NET and am stuck on how to declare an anonymous type in VB.NET.[code]How do you translate C#'s new { ... } syntax into VB.NET?
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Mar 17, 2010
Every LINQ example I have seen for VB.NET anonymous types claims I can do something like this:
[code]...
Now when I go to iterate through the collection(see example below), I get an error that says "Name "x" is not declared. For Each x in Infos It's like VB.NET doesn't understand that Infos is a collection of anonymous types created by LINQ and wants me to declare "x" as some type. (Wouldn't this defeat the purpose of an anonymous type?) I have added the references to System.Data.Linq and System.Data.DataSetExtensions to my project. Here is what I am importing with the class:
[code]...
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Mar 10, 2010
Basically, I wish to fetch a filtered set of objects from the database (Oracle 9.2) based on the id property of the object PsalertsEvent. The code being executed is:
Public Overloads Function GetAll(ByVal laterThan As Long, ByVal filteredPsalertsEvents As IList) As IList Implements IPsalertsEventRepo.GetAll
'Get all psalerts events with an ID greater then the specified laterThan parameter
filteredPsalertsEvents = MyBase.NHibernateSession.CreateQuery("from PsalertsEvent p where p.id > " & laterThan).List
[Code]...
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Feb 4, 2010
I just read this article about the Entity Framework 4 (actually version 2).Entity Framework seems to offer a huge improvement over its first release. Thus, I have never ever used EF in any project, since I think EF is not mature enough in comparison to NHibernate.NHibernate and its current contributions of FluentNHibernate and Linq for NHibernate by Ayende RahienMy feeling is that Microsoft is solely trying to gain terrain it has lost in favor of NHibernate when the 2nd version of NHibernate came out.Nevertheless, my concerns are the followings (not in particular order):Will EF4 tend to be less XML-verbose?Will EF4 be compatible with other underlying datastore than just SQL Server?What are the greatest benefits of going with EF4 instead of FluentNHibernate or NHibernate itself.
NHibernate is a great tool, I guess everyone agrees. Due to its predecessor Hibernate, we may easily find documentions and tutorials and sample applications to get acquainted with it. This is not the case for FluentNHibernate. Particularly as per the project I'm working on right now which demands that I investigate further about NHibernate and its options (FluentNHibernate for instance) in order to document the rules of usage and the best practices of NHibernat and FluentNHibernate technology. Thus, being handcuffed with VB.NET, being a C-Style developer, I can't find some syntax equivalencies in VB.NET for the examples provided, though I made I way so far
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Oct 26, 2010
I would like to ask if you can use VB.NET for NHibernate and Fluent Nhibernate?I have searched the web, but I can't seem to get a detailed or explicit statement that tells that one can use VB.NET for NHibernate and with Fluent.
Many of the samples in the NHibernate site are made in C#. That's why I was wondering if I can't use VB.NET when using NHibernate.
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Jul 9, 2009
I'm a Linq noobie, maybe someone can point me in the right direction. What's wrong here? These anonymous types seem to have the same signatures.
[Code]...
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Mar 1, 2011
I have a datagridview in a form that is dynamically bound to a datatable. When the user clicks a button I update certian columns of the current row with code like this:
Dim i As Integer = myDataGridView.CurrentRow.Index
Me.myDataGridView.Item("closed", i).Value = DBNull.Value
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May 1, 2009
I'm working with Visual Basic 2008 Express. My application opens with the Terms screen, a form that asks the user to declare his acceptance of certain terms and conditions or to decline. If he accepts, the app opens the main screen, giving him access to all the app's facilities. If he declines, the app gives him a message and then closes. Whether he chooses to accept or decline, the app puts his decision in My.Settings so that it can be used next time the app is opened. In this way he is presented with the Terms screen on the next opening if he declined on the last run. But if he accepted on the last run, he is presented with the main screen on his next opening.
All works fine when I do a debug run. But when I build and publish the app onto my desktop it opens with the Main screen instead of the Terms screen.
why it works on F5 but not after publishing?
Public
Class frmTerms
Dim Accept As Boolean
[Code].....
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Sep 4, 2009
I need to very quickly write an exe system on a laptop where when the laptops are connected to the network they read a database table and store the data locally, so staff can use the laptop while they roam.The laptops have quite small capacity and the company would prefer not to use SQL Express or Access.
My question is, can the data initially be downloaded into the exe application via a dataadapter and dataset, and will that dataset the retain the downloaded data, or will I need to ensure the dataset is written to an XML file and then loaded/unloaded each time the laptop application is started while the staff are travelling ?
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Jun 6, 2012
I am a web developer who now has to change a Windows service. I never worked on a Windows service before. I have a several programs that can run within this service. I want to persist a value of a variable from program to program.
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Mar 21, 2012
I'm having some problems in persisting the viewstate on postback for a Control (vb.net)
here's some code i've put in my control[code]...
I'm setting EnableViewState = "true" everywhere i can, but still no result. Do i really need to set those properties here. (ViewStateMode and EnableViewState) If not, where should i handle this and what is the difference between those properties?
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Nov 1, 2009
I have a class with a Property called 'Value' which is of type Object.Value can be of any type, a structure, a class, an array, IList etc.My problem is with the setter and determining whether the value has changed or not.This is simple enough for value types, but reference types and lists present a problem.For a class, would you assume that the Equals method has been implemented correctly, or just assume that the value has changed every time the setter is called?If I did assume it's changed, then perhaps I should assume it for value types as well, so that the behaviour is consistent.
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Dec 9, 2010
I have been searching for quite a while now but i am unable to find the answer to the following. I am storing a key pair in Windows Store, and recently started receiving the "Keyset does not exist" error. Investigating a bit further i found out it could be two things, 1 - The private key is not stored with the persist key set attribute (X509KeyStorageFlags.PersistKeySet) and 2 - access rights to the key. I have tried both 1 and 2 with no success on one machine (in my machine it works apparently). The strange thing is that when i look into MicrosoftCryptoRSAMachineKeys (and S-1-5-18) the key remains there but only for a period of time then it is deleted which means that it is not persisting.
//If decoded then save as RSACryptoServiceProvider
newCert.PrivateKey = DecodePrivateKey(privateKeyFile, pkPassword)
if (newCert.PrivateKey == null)
[Code]....
I have just found out today that since i am doing this through a WCF service, the application pool is deleting the private key when it reaches its idle time limit so i am completely sure that it is the application pool the one disposing of the private key which causes the key to be deleted from the MicrosoftCryptoRSAMachineKeys and S-1-5-18 folders. Today i left a test running where i disabled Idle time shut down from the application pool bu i am still not sure if the private key will stop persisting with a restart or something like that?
Would anybody know how to make the application pool stop deleting my private keys?
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Jan 13, 2011
I need some general advice about using ListView. The program was originally written in VB2002, but now it's running in VB2008.The results of my program would typically be a ListView of 30 lines by 8 columns. I need to be able to save this data so that it persists after I close the program. There will never be a need to manipulate the data, so I'm looking for something simple. (There will be a need to print it.) I'm presuming that I need to link to a database to save the data. Correct? If so, can I use the one in Microsoft Works (which I already have), or do I need to get Microsoft Access, or is there some other better (simpler?) alternative?
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Oct 10, 2011
I'm looking for a simple, efficient way to get the position of the browser vertical scrollbar and save it into a session variable in an ASP page. What I'm trying to do is when the user changes a page I've the scroll position stored in a session variable so that when the user returns to the page the page will scroll to their last position.Is there a way to do this? I've seen examples of persisting the scroll position on postback but nothing yet doing exactly what I'm trying to do [code]
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Jun 16, 2010
I need to save the controls location and size on the parent form to file. My aim is to be able to simply copy that file to the path where an instance of my program is running and then it automatically applies the previously saved layout of controls. How can I use My.Settings to do that or is there another better option?
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Jul 26, 2011
Sorry for the extra long title, Here's what I want to do.I want to give the user the option of using or not using specific features of the program.If I can set a simple yes or no value that wil persist each time the program run and then depending on the variable turn off or on the feature at start
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